Code
C057C
Generic
C — Chassis
Brake Booster Temperature Sensor B CircuitRange/Performance
Views:
UK: 13
EN: 22
RU: 21
AI status
Completed
Completed
100%
Causes
- Open or short in sensor wiring harness (power, signal, or ground)
- Corroded, loose, or damaged sensor connector or pins
- Failed or degraded brake booster temperature sensor (thermistor)
- Water ingress or contamination at the sensor or connector
- Incorrect reference voltage from control module or poor module ground
- Intermittent fault due to vibration or broken wire
Symptoms
- C057C stored in the vehicle’s diagnostic memory and MIL or chassis warning lamp may be illuminated
- Brake-related warnings or degraded brake system performance messages (vehicle dependent)
- Inconsistent brake booster temperature readings in live data (out-of-range or frozen value)
- Occasional or permanent loss of temperature signal for sensor B
- Related faults logged for other brake sensors or communication if fault progresses
What to check
- Read and record freeze-frame and live-data values for brake booster temperature sensor B with a scan tool
- Perform a visual inspection of the sensor, harness, and connector for damage, corrosion, or contamination
- Backprobe the sensor connector and monitor signal voltage while varying ambient temperature if safe
- Check connector terminals for continuity and proper seating; wiggle harness while monitoring live data for intermittent faults
- Measure resistance of the sensor (engine off, harness disconnected) and compare to expected chart if available
- Inspect for shorts to battery or ground using a multimeter (backprobe/connector side)
Signal parameters
- Typical sensor interface: 2‑wire thermistor (resistance changes with temperature) or 3‑wire with reference and signal (vehicle dependent)
- Nominal signal voltage range: ~0.1–4.9 V depending on temperature (vehicle-specific); check OEM data
- Typical resistance behavior for NTC thermistor: higher resistance at low temperature, lower resistance as temperature rises (example ~10 kΩ at 25°C — vehicle-specific)
- Reference supply commonly 5 V or regulated reference from control module (verify with service manual)
- Response time:
Diagnostic algorithm
- Connect an appropriate scan tool, read DTCs, record freeze-frame and live-data for brake booster temperature sensor B. Note related codes.
- Visually inspect the sensor, boot, connector, and harness for corrosion, damage, or signs of water ingress. Repair obvious damage.
- With ignition ON (engine off) backprobe the sensor connector and measure signal voltage and reference voltage with a DMM. Compare to expected ranges from OEM data.
- With the harness disconnected, measure sensor resistance at ambient temperature and, if safe, vary temperature (e.g., warm with heat gun briefly or cool with ice) to verify resistance changes correspondingly. Compare to expected resistance vs temperature chart.
- Check continuity and resistance between the sensor connector and the control module pins to confirm there is no open circuit and to detect high-resistance connections. Check for shorts to battery and ground.
- Perform a wiggle test on harness and connector while monitoring live data for intermittent changes. Repair or secure any damaged wiring or loose terminals.
- If electrical checks are within specification but the sensor reading is still out of range, replace the sensor B with a known-good part and clear codes. Re-test (freeze-frame/live data) and perform a road or operation cycle to confirm repair.
- If fault persists after sensor replacement and wiring checks, inspect the brake control module power/ground and communication lines, and consult OEM diagnostic flow for possible module failure or software update.
Likely causes
- Damaged wiring between sensor B and the brake control module
- Corroded/loose connector at sensor B
- Failed temperature sensor element (out-of-spec resistance/voltage)
- Short to battery voltage or ground on the sensor signal
- Connector contamination (water/oil) causing intermittent readings
Fault status
Status
Brake Booster Temperature Sensor B circuit out of range or performance fault detected — check sensor, wiring, connectors, and module inputs.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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